This is simple adjustable smartphone and tablet stand.
You can easily and quickly change the angle.
There is a rubber band inside.

Update(2020/8/23):

In the current condition of my printer, gear part was too tight. So, I made the gap slightly larger. Only Male was modified and it became v3.2.

The diameter of cylindrical part of V32b is 0.1mm smaller than that of V32a.
V32a-Male.stl and V32b-Male.stl are only for checking gaps.
Please print SmartPhone(Wide)StandV31-Female.stl, V32a-Male.stl and V32b-Male.stl first to find good combination,
then print SmartPhone(Wide)StandV32?-Male.stl.

If the cap is too tight, please shrink only x and y of cap slightly.

This is remix of https://www.thingiverse.com/thing:3048358
To increase the rigidity, the legs became thicker.
And I made a movie file for assembly.
https://youtu.be/WAh2LkIBGTM

Update(2020/5/3):
I made thinner models for Male of V31.
Also, small test models were made.

Update(2019/8/26):
Resolution of V4 models were improved.
Thank you for comment from Nicolinux!

Update(2018/11/11):
Thanks to Saur0n, wider version was modified (V4).
If you use silicon/rubber pads, it becomes more stable.
You can use same cap for this, too.

Update(2018/10/31):
Based on the comments of Saur0n, wider version(+2cm) was added. (Thank you, Saur0n!)
Although I did not use support with my printer, I modified the model by using chamfer instead of fillet. I hope the printing becomes easy even without using support.